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c++内存流
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1、MemoryStream.h文件内容
ifndef _MEM_STREAM_H_
#define _MEM_STREAM_H_ #include <string> class CMemoryStream
{
public:
explicit CMemoryStream(std::size_t size)
{
m_pBuffer = new unsigned char[size];
memset(m_pBuffer, 0, size);
m_nSize = size;
m_nCurrentWritePos = 0;
m_nCurrentReadPos = 0;
m_bManageMemory = true;
} CMemoryStream(void* buffer, std::size_t size)
{
m_pBuffer = (unsigned char*)buffer;
m_nSize = size;
m_nCurrentWritePos = 0;
m_nCurrentReadPos = 0;
m_bManageMemory = false;
} ~CMemoryStream()
{
if (m_bManageMemory)
{
delete [] m_pBuffer;
}
m_pBuffer = NULL;
} public:
template<typename T>
CMemoryStream& operator <<(const T& value)
{
if (m_pBuffer &&
m_nCurrentWritePos < m_nSize)
{
*(T*)(m_pBuffer + m_nCurrentWritePos) = value;
m_nCurrentWritePos += sizeof(T);
} return *this;
} template<typename T>
CMemoryStream& operator >>(T& value)
{
if (m_pBuffer &&
m_nCurrentReadPos < m_nSize)
{
value = *(T*)(m_pBuffer + m_nCurrentReadPos);
m_nCurrentReadPos += sizeof(T);
} return *this;
} CMemoryStream& operator <<(const char* pBuffer)
{
if (m_pBuffer &&
m_nCurrentWritePos < m_nSize)
{
std::size_t size = strlen(pBuffer) + 1;
memcpy(m_pBuffer + m_nCurrentWritePos, pBuffer, size);
m_nCurrentWritePos += size;
} return *this;
} CMemoryStream& operator <<(const std::string& str)
{
return operator <<(str.c_str());
} CMemoryStream& operator >>(const char* &pBuffer)
{
if (m_pBuffer &&
m_nCurrentReadPos < m_nSize)
{
const char* p = (const char*)(m_pBuffer + m_nCurrentReadPos);
std::size_t size = strlen(p);
if (size + m_nCurrentReadPos < m_nSize)
{
pBuffer = p;
m_nCurrentReadPos += size+1;
}
} return *this;
} CMemoryStream& operator >>(std::string& str)
{
if (m_pBuffer &&
m_nCurrentReadPos < m_nSize)
{
const char* p = (const char*)(m_pBuffer + m_nCurrentReadPos);
std::size_t size = strlen(p);
if (size + m_nCurrentReadPos < m_nSize)
{
str.assign(p, p + size);
m_nCurrentReadPos += size+1;
}
} return *this;
} CMemoryStream& operator <<(const wchar_t* pBuffer)
{
if (m_pBuffer &&
m_nCurrentWritePos < m_nSize)
{
std::size_t size = (wcslen(pBuffer) + 1) * sizeof(wchar_t);
memcpy(m_pBuffer + m_nCurrentWritePos, pBuffer, size);
m_nCurrentWritePos += size;
} return *this;
} CMemoryStream& operator <<(const std::wstring& str)
{
return operator <<(str.c_str());
} CMemoryStream& operator >>(const wchar_t*& pBuffer)
{
if (m_pBuffer &&
m_nCurrentReadPos < m_nSize)
{
const wchar_t* p = (const wchar_t*)(m_pBuffer + m_nCurrentReadPos);
std::size_t size = wcslen(p) * sizeof(wchar_t);
if (size + m_nCurrentReadPos < m_nSize)
{
pBuffer = p;
m_nCurrentReadPos += size+sizeof(wchar_t);
}
} return *this;
} CMemoryStream& operator >>(std::wstring& str)
{
if (m_pBuffer &&
m_nCurrentReadPos < m_nSize)
{
const wchar_t* p = (const wchar_t*)(m_pBuffer + m_nCurrentReadPos);
std::size_t size = wcslen(p) * sizeof(wchar_t);
if (size + m_nCurrentReadPos < m_nSize)
{
str.assign(p, p + size);
m_nCurrentReadPos += size+sizeof(wchar_t);
}
} return *this;
} private:
CMemoryStream(const CMemoryStream& memstream); const CMemoryStream& operator =(const CMemoryStream&); private:
unsigned char* m_pBuffer;
std::size_t m_nSize;
std::size_t m_nCurrentWritePos;
std::size_t m_nCurrentReadPos; bool m_bManageMemory;
}; #endif
2、使用示例：
#include "stdafx.h" #include "MemoryStream.h" int _tmain(int argc, _TCHAR* argv[])
{
CMemoryStream mem(100); int a = 100;
int b;
const char* p1 = "123456";
const char* p2 = NULL;
const std::string s1 = "abcedfg";
std::string s2;
const wchar_t* p3 = L"789456";
const wchar_t* p4 = NULL;
const std::wstring s3 = L"mmm";
std::wstring s4;
double d1 = 100.5;
double d2 = 0;
float f1 = 200.5;
float f2 = 0; mem << a;
mem << p1;
mem << s1;
mem << p3;
mem << s3;
mem << d1;
mem << f1; mem >> b >> p2 >> s2 >> p4 >> s4 >> d2 >> f2; return 0;
}
